340 STUDIES IN SEEDS AND FRUITS 



chestnut {Msculus Hippocastanum)^ the seeds of the two-seeded 

 fruits are smaller and lighter than those of the single-seeded 

 fruits, in this case the decrease in weight being about i8 

 per cent. 



(^b) With regard to legumes the indications supplied by 



the 126 dry pods of Albizzia Lebbek are particularly valuable, 



all of them being obtained at the same time from the same 



tree. Here the seeds range in number from i to 12 ; and 



for each number of seeds from 8 to 13 pods were employed. 



Here it will be seen that whilst the legume doubles its length, 



and increases its weight sevenfold, the average weight of a 



seed changes but little. The extreme range of the variations 



amounts to only about 13 per cent, of the average weight 



of the seed, the variations themselves being evidently 



fortuitous in character. The testimony of the legumes of 



other plants named in the tables cannot carry much weight, 



because the materials are insufficient. But I would gather 



from the cases of Ulex europaus and Abrus precatorius that with 



small pods the seeds keep their weight as they increase in 



number and the pods increase in size. 



The study of And now, before leaving this subject of the relation 



between the between the number of seeds and the weight and size of 



seSsand^the ^^^ ^^^^^ ^^'^ ^^^ parts, it is necessary to point out that, 



proportions however suggestive the indications may be, we have not yet 



of the fruit ,. , SS . , , , , £ ,. 11 ,/ 



opens up a discovered an end or the thread or this tangled problem. 



problem. Yet these figures may serve to direct our efforts in the right 

 direction. Thus the first question they will lead us to put 

 will be the very pertinent one relating to the causes and 

 nature of the variation in the number of seeds in the fruits 

 of the same individual plant. If the relative size of the 

 fruit is determined on fixed principles by the number of 

 seeds, it would be natural to inquire what determines the 

 number of seeds. 



But several subsidiary questions arise when we peruse 

 the columns of the tables. Why, for instance, does a single- 

 seeded pod differ from other many-seeded pods on the same 



